1. Field of the Invention
The present invention relates to an adjustable wrench, and more particularly, to one that allows easy and fast adjustment, and firm positioning.
2. Description of the Prior Art
In the prior art of the present invention as illustrated in FIG. 7, a wrench is provided with a handle 8 and a slide 9. A multiple of tooth 81 is provided on one side of the handle 8, a clamping member 82 to hold a bolt 7 is provided at the end of the handle 8, an axis 91 is provided at one side of the slide 9, said axis 91 is pivoted to a thumb 92 held against by a passive flexible tab 93, and one end of said thumb 92 is provided with a multiple of tooth 921 to ratchet the tooth 81 from the handle 8.
In use, a user has to press the thumb 92 to make the tooth 921 of the thumb 92 to disengage from the tooth 81 of the handle 8 before moving forward or backward the handle 8 to change the distance between the clamping piece 82 and the inner edge 94 of the slide 9. In the process of moving the handle 8, the tooth 921 from the thumb 92 must be completely cleared away from the tooth 81 of the handle 8. While pressing the thumb 92, the handle with inherited heavy weight must be pushed with a force that prevents an easy movement precisely by one tooth for the handle 8. The difficulty in inching just for a distance of one tooth results in the creation of a space between the clamping piece 82 and the bolt 7 to be turned, and furthermore in the failure of securing the bolt 7.
Whereas the thumb 92 is pivoted to the slide 9 by the axis 91, and is ratcheted to the tooth from the handle 8 due to the plunging from the flexible tab 93. In use, the thumb 92 must be pressed to completely disengage its tooth 921 from the tooth 81 of the handle 8 before pushing the handle 8 to adjust the distance between the clamping piece 82 and the inner edge of the slide 9. In case of any failure to press the thumb 92 all the way to the end to move the handle 8, the thumb 92 can get easily worn out since certain piece of the tooth 921 close to the axis 91 has not yet disengaged from the tooth 81 of the handle 8. When said piece of the tooth 921 is worn out, with only the remaining tooth 921 ratcheted to the tooth 81 of the handle 8 resulting in sliding, thus to serious affect the positioning effect of the thumb 92.
Furthermore, the distance between the clamping piece 82 and the inner edge 94 of the slide 9 is adjusted by pushing the handle 8. Since the bolt 7 is available indifferent sizes, and the adjustment can only be achieved by the multiplex of pitch of the tooth 81, the adjustment fails to be made exactly depending on the individual size of the bolt 7. If the pitch of the tooth 81 is made wider, the greater ratcheting force is provided, but the range for adjustment gets narrower. On the contrary, if the pitch of the tooth 81 is made narrower, the ratcheting force gets too small to cause sliding.